ETCHING AND POLISHING STUDIES ON MGO CRYSTALS IN ACIDS

The effect of temperature and concentration of a variety of inorganic and organic acids, on etch rates is investigated. It is observed that in HCl, CH3COOH and C2H5COOH the value of activation energy of dissolution and that of the corresponding pre‐exponential factor are sensitive to acid concentration. In H3PO4 and HCOOH, while the value of activation energy remains unchanged, only the pre‐exponential factor changes. The concentration dependence of etch rates in HCl, CH3COOH and C2H5COOH is different from that of H3PO4 and HCOOH. In the former acids maximum and minimum values are obtained on the etch rate versus concentration curves, but in the letter ones etch rate slowly increases with concentration. The influence of temperature on the maximum value of etch rate on the etch rate‐concentration plots of HCl, and that of the degree of dissociation of the acids on etch rate are also studied. The observations are discussed, and important conclusions are enumerated. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim